An accumulator tank, hereinafter called an accumulator, is often disposed between a refrigerant evaporator and the suction port of a refrigerant compressor in a vapor compression refrigeration system. The function of the accumulator is to collect liquid refrigerant which may exit the evaporator and prevent it from entering the compressor until it can be evaporated.
It is common to add heat to the accumulator to enhance hot gas heating and/or defrost cycles by evaporating greater quantities of liquid refrigerant. This accelerates the amount of refrigerant available in the active refrigerant circuit for use in the hot gas heating or defrosting cycle. Users of heated accumulators, however, often experience certain problems. A first problem encountered is in properly controlling the heat input to the liquid refrigerant to prevent boil-over, which results in defeating the primary purpose of the accumulator. Boil-over allows excessive liquid refrigerant to be carried over into the suction line and into the compressor, an action called "slugging". Slugging is to be avoided, as it may be damaging to the compressor head, and other moving compressor parts, shortening the useful operating life of the compressor. A second problem encountered is in the inability to heat the liquid refrigerant entering the accumulator rapidly enough to achieve a desired rapid build up of refrigerant in the active refrigerant circuit during heating and defrost operations. Failure to heat the liquid refrigerant rapidly results in slow build-up of heat for heating a conditioned load to hold a selected set point temperature during a heating cycle, and slow build-up of heat for heating an evaporator coil during a defrosting cycle. Thus, the heating and defrosting cycles are longer than desired.
It would be desirable, and it is an object of the present invention, to provide a heated accumulator constructed to heat liquid refrigerant entering the accumulator very rapidly, without resulting in the hereinbefore mentioned detrimental boil-over of liquid refrigerant into the suction line and refrigerant compressor.